The present invention relates to data communications equipment and, more particularly, to the simultaneous transmission of voice and data over a single Public Switched Telephone Network (PSTN) line.
Simultaneous Voice and Data (SVD) technology permits simultaneous voice and data communications between a pair of users within the bandwidth provided by a single xe2x80x9cplain old telephone servicexe2x80x9d (POTS) line. In operation, a high speed voice-band modem carries data in the usual manner. When either user wishes to communicate to the other by voice, a signal is sent via a standard V70 Protocol message. Once the other user acknowledges the message, a voice channel is opened and a portion of the total modem rate (e.g., 8 KB/S) is allocated for carrying the digitally compressed voice data. As a result, the two parties can simultaneously communicate by both voice and data. To be able to convert between analog data and compressed digital voice data, and to handle the signaling protocol, both parties must have SVD capability. The basic operation of an SVD modem is described in U.S. Pat. No. 5,448,555 to Bremer et al.
Technology has been developed which enables an SVD user to have a voice conversation and a data connection at the same time, but with different parties. Under this prior art technique, a central office (e.g. an inter-exchange carrier such as ATandT) of a PSTN provides a xe2x80x9clocal loopxe2x80x9d SVD service in which both voice and data calls with the user co-exist over a POTS line, and the voice and data portions of these calls are routed to separate parties. To accomplish this result, the central office must include a modem pool that has both SVD-capable modems and standard (e.g., CCITT V.32 compatible) modems. A user with an SVD modem establishes an SVD link with the SVD modem of the central office. The SVD modem of the central office then separates the voice and data portions of the voice-band signal received from the local loop for separate transmission by the central office to different parties. The voice portion of the SVD signal receives standard voice-call handling from the central office for transmission to the party that is a part of the voice-call. The data portion of the SVD signal is routed through the standard modem of the central office for transmission to the party that is a part of the data-call. As a result, only the SVD user is required to have an SVD-capable modem, yet the SVD user can have both a voice connection and a data connection over a single xe2x80x9ctip/ringxe2x80x9d type telephone line. This kind of arrangement is described in U.S. Pat. No. 5,513,251 to Rochkind et al. and U.S. Pat. No. 5,625,677 to Feiertag et al., and in published European Patent Application No. EP 674,420 which cites U.S. patent application Ser. No. 216,373 as a priority application.
In the above described call-handling system, the central office of the PSTN must be equipped with the additional modems to be able to detect the type of incoming call (modem/voice or SVD) for a particular telephone number and process that call properly. This is very expensive because all of the central offices that want to provide this functionality must be upgraded to include SVD modems and standard data modems. If the central office to which User 1 is connected is not equipped with the specialized modems, User 1 cannot carry on this simultaneous voice and data communication with different parties. Further, the central office can accomplish the simultaneous voice/data communication only because it has the capability of establishing a local loop between the central office and the caller with the SVD modem.
Permits a first party (hereinafter xe2x80x9cthe clientxe2x80x9d) to a data communication connection with a second party (hereinafter xe2x80x9cthe serverxe2x80x9d) on a regular voice-band PSTN connection to accept and originate voice calls from and to anywhere on the PSTN while maintaining the data communication with the server. This is accomplished by adding additional functionality at the location of the server and by utilization of existing xe2x80x9cCall Forwardingxe2x80x9d and xe2x80x9cCaller-Idxe2x80x9d technology.
In one embodiment, the call handling is accomplished by the steps of establishing a SVD data connection between a first party and a second party; and establishing a voice call between the first party and a third party; wherein the voice call and the data call co-exist on a regular voice-band PSTN line between a switching system of said second party and terminal equipment of said first party, and the telephone number of said second party and the telephone number of said third party are different.
In a preferred embodiment all calls that are incoming to the first party are automatically forwarded to the second party; and the second party manages the connection of the voice-call between said first party and said third party. Upon initiation of a voice-call from said third party to said first party, said second party receives said incoming call from said third party; determines the identity of the calling party (said third party) and said party being called (said first party); and establishes a connection between said third party and said first party on the same regular voice-band PSTN connection that is being used for said data-call between said first party and said second party.
In a more preferred form, the second party comprises an internet service provider or a server independent of the PSTN.
In another embodiment, the additional step of establishing voice calls between a plurality of parties located at the same location as said first party and an equal number of parties located elsewhere is performed. For the duration of the SVD data connection, all calls that are incoming to the first party are forwarded to the second party, and the second party manages all incoming/outgoing calls to/from the first party by forwarding incoming calls to the first party over the PSTN line on which the SVD data connection is established and by forwarding all outgoing calls of the first party to a destination party over the PSTN line.
In an alternative embodiment, call handling is accomplished by establishing a data connection between a first party and a second party over a regular voice-band PSTN line; and for the duration of the data connection, all calls that are incoming to the first party are forwarded to the second party, and the second party manages all incoming/outgoing calls to/from the first party by forwarding all of the incoming calls to the first party to an incoming call processor.
A hardware embodiment of the present invention comprises a server for routing voice/data calls to/from a first SVD modem via a PSTN, the server comprising a second SVD modem, coupled to the PSTN, for receiving a transmission from the first SVD modem, the transmission having a voice channel and a data channel; a first caller identification circuit, coupled to the second SVD modem and to said PSTN, for identifying a party being called from the first SVD modem and a party calling to the first SVD modem; a second caller identification circuit, coupled to the PSTN; and a controller, coupled to the second caller identification circuit and the second SVD modem, for controlling the routing of voice/data calls to/from the first SVD modem via the PSTN based on the identification made by the first and second caller identification circuits.